[cfe-commits] r173377 - in /cfe/trunk: include/clang/AST/Expr.h include/clang/Basic/DiagnosticASTKinds.td include/clang/Basic/DiagnosticSemaKinds.td include/clang/Sema/Sema.h lib/AST/ExprConstant.cpp lib/Sema/SemaChecking.cpp lib/Sema/SemaDecl.cpp lib/Sema/SemaExprCXX.cpp lib/Sema/SemaStmt.cpp test/Sema/switch-1.c

[John McCall]

On Jan 24, 2013, at 3:11 PM, Richard Smith <richard at metafoo.co.uk> wrote:
> On Thu, Jan 24, 2013 at 2:11 PM, Fariborz Jahanian <fjahanian at apple.com> wrote:
>> Author: fjahanian
>> Date: Thu Jan 24 16:11:45 2013
>> New Revision: 173377
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=173377&view=rev
>> Log:
>> Patch to check for integer overflow. It has been
>> commented on and approved by Richard Smith.
>> 
>> Modified:
>>    cfe/trunk/include/clang/AST/Expr.h
>>    cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td
>>    cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>>    cfe/trunk/include/clang/Sema/Sema.h
>>    cfe/trunk/lib/AST/ExprConstant.cpp
>>    cfe/trunk/lib/Sema/SemaChecking.cpp
>>    cfe/trunk/lib/Sema/SemaDecl.cpp
>>    cfe/trunk/lib/Sema/SemaExprCXX.cpp
>>    cfe/trunk/lib/Sema/SemaStmt.cpp
>>    cfe/trunk/test/Sema/switch-1.c
>> 
>> Modified: cfe/trunk/include/clang/AST/Expr.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Expr.h?rev=173377&r1=173376&r2=173377&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/AST/Expr.h (original)
>> +++ cfe/trunk/include/clang/AST/Expr.h Thu Jan 24 16:11:45 2013
>> @@ -570,6 +570,9 @@
>>   /// integer.
>>   llvm::APSInt EvaluateKnownConstInt(const ASTContext &Ctx,
>>                           SmallVectorImpl<PartialDiagnosticAt> *Diag=0) const;
>> +
>> +  void EvaluateForOverflow(const ASTContext &Ctx,
>> +                           SmallVectorImpl<PartialDiagnosticAt> *Diag) const;
>> 
>>   /// EvaluateAsLValue - Evaluate an expression to see if we can fold it to an
>>   /// lvalue with link time known address, with no side-effects.
>> 
>> Modified: cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td?rev=173377&r1=173376&r2=173377&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td (original)
>> +++ cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td Thu Jan 24 16:11:45 2013
>> @@ -106,6 +106,9 @@
>>   "(skipping %0 call%s0 in backtrace; use -fconstexpr-backtrace-limit=0 to "
>>   "see all)">;
>> def note_constexpr_call_here : Note<"in call to '%0'">;
>> +def warn_integer_constant_overflow : Warning<
>> +  "overflow in case constant expression results in value %0 of type %1">,
>> +  InGroup<DiagGroup<"integer-overflow">>;
> 
> This diagnostic text is wrong, since we're checking for overflow in
> all expressions, not just case constant expressions.

It's also confusingly worded.  A better diagnostic, if we keep a specialized
message for case expressions, would be something like:
  "overflow in 'case' expression;  resulting value is %0 of type %1"
In particular, the quotation marks are importing in order to prevent
people from interpreting "in case ..." as the common English idiom.
It is also unnecessary to point out that this is a constant expression.

John.